The present invention relates generally to crop harvesting machines commonly referred to as disc mower conditioners and, more particularly, to a disc cutterbar drive configuration utilizing a timing belt to transfer rotational power between respective disc cutters having knives mounted thereon in relative overlapping, yet noninterfering paths of travel.
Typically, disc cutterbars used on implements such as disc mower-conditioners include a transmission casing mounting a plurality of disc cutters rotatable about an upright axis of rotation along the transverse width thereof. Each disc cutter is provided with a drive gear meshed with adjacent idler gears so as to form a power transmission train to transfer rotational power between all of the disc cutters. This gear driven drive train is expensive to manufacture and to maintain as it requires an oil tight transmission casing to encapsulate an oil bath for the precision intermeshing gears.
Gear driven disc cutterbars further suffer from an inherent high level of noise during operation due to the intermeshing gear teeth. Susceptibility to damage is also a significant problem with gear driven disc cutterbars because of the precise nature of the operation thereof. Any damage to a drive gear within the enclosed transmission casing normally results in additional damage to adjacent gears. Also, a required amount of lubrication is needed to be maintained within the oil tight transmission casing to dissipate the heat generated by the operation of the meshed gears and to provide sufficient lubrication therefor.
Attempts to provide a belt driven disc cutterbar have been made in the past; however, slippage between the driving power transmission belt and the engaged sheave creates interference problems between the rotating knives on adjacent discs as the path of rotation of the adjacent knives must overlap to prevent areas of uncut crop material between discs. One solution to this problem is to place the path of rotation of the respective adjacent rotating knives in different planes, such as seen in U.S. Pat. Nos. 3,138,911 and in 3,457,714. Such solutions provide an unacceptable scalloped-shaped cut compared to the uniform level of cut obtained from the gear driven disc cutterbar. Furthermore, it is desirable to time the relative rotations of adjacent disc cutters to minimize the simultaneous occurrence of adjacent knives within the overlap area therebetween, thereby minimizing the chance for interference if one of the knives have been damaged and bent out of the normal path of rotation.
Accordingly, it would be desirable to provide a belt driven disc cutterbar whose operation and performance would at least approximate conventional gear driven disc cutterbars by providing a means for timing the rotation of the disc cutters while providing a means for minimizing interference should the timing between adjacent disc cutters be interrupted.